1. Field of the Invention
The present invention relates to a microphone.
2. Description of the Related Art
In some conventional waterproof microphones, an acoustic terminal unit is provided on an internal center portion of a housing having openings on opposing surfaces, waterproof vibration membranes are provided to cover the openings of the housing, and stainless meshes are provided on the inner sides of the waterproof vibration membranes with spaces therebetween, as described in Japanese Patent No. 3629084.
When this type of conventional waterproof microphone is normally being used underwater, if an external sound is transmitted to the waterproof vibration membranes via the openings of the housing, the waterproof vibration membranes are vibrated according to the sound pressure level of the transmitted sound, and the vibration is transmitted to the acoustic terminal unit via the interspaces of the stainless meshes, whereby the microphone serves as a normal microphone. In this case, the acoustic terminal unit is waterproofed by the waterproof vibration membranes, and functions as a waterproof type.
On the other hand, when water pressure extremely increases while the conventional waterproof microphone is being used underwater, the waterproof vibration membranes tend to be resiliently deformed toward the inside by an extreme amount. However, the stainless meshes provided on the inner sides of the waterproof vibration membranes with spaces therebetween inhibit these extreme inward resilient deformations of the waterproof vibration membranes, whereby the waterproof vibration membranes are prevented from being ruptured by the extreme increase in the water pressure (external pressure).